Boso is Cookie Monster's cousin on the Sesamstrasse spin-off series Pizza mit Biss. He made his appearance in the pilot episode "Der unheimliche Gast" ("The Eerie Guest") in 2017. Despite his scary looks and clumsy behavior, the character turns out to be a kind and friendly soul. The character hails from the fictional country of "Schlamponien" (presumably "Shlamponia" in English), speaking only "Schlamponisch" ("Shlamponian"); even calling his cousin Cookie Monster only by his Shlamponian name "Krossi."